The invention relates to a heat storage means and more particularly to a latent heat storage means for vehicle heating systems run on waste engine heat, comprising an inner container accommodating a storage core, an outer container surrounding the inner container with a clearance to constitute a preferably evacuated insulating space, two ducts running from the outside through the insulating space to the inner container, of which one functions as a supply duct for a heat vehicle fluid and the other functions as a return duct therefor, and the inner container is suspended at two end walls, via a respective group of ribs with a low thermal conductivity, on the outer container, between a first end wall of the inner container and the outer container at least one spring is so arranged that it tends to change the distance apart of the opposite end walls of the inner container and of the outer container and between the container wall connecting the two end walls of the inner container and the adjacent container wall of the outer container the insulating space has its minimum thickness.
A heat storage means of this type is described in the German patent publication 3,725,165 A.
In order to prevent losses of the stored heat as far as possible high efficiency insulation is necessary between the inner container and the outer container, in which respect it is also desirable for the insulation to have a minumum volume so that the overall volume of the heat storage means may be kept small, as is necessary in the case of installation in motor vehicles, because there is here only a small amount of space available for additional equipment. In order not to excessively increase the weight of the vehicle the weight of such a heat storage means should be kept low.
A form of insulation which more particularly complies with these requirements is a vacuum space left between the inner and outer containers. In this respect means for locating the inner container within the outer container is necessary, which for its part should have a minimum weight and should only allow minimum heat losses.
In the case of the known heat storage means there was therefore the purpose of fixing the inner container in an extremely simple way in the outer container, such fixing means having to satisfy furthermore the requirements for a minimum weight and allowance for expansion due to changes in temperature.
The fixation of the inner housing in the outer housing by means of suspension leads to the advantage that essentially only tensile forces have to be transmitted so that small cross section become possible, which on the one hand reduce the necessary weight and on the other hand keep the heat losses occurring low. The spring holds the suspension under tension and allows for the effects of thermal expansion and suppresses or damps undesired vibrations.
While attempting to keep the overall volume of the heat storage means as low as possible, it has been possible to diminish the thickness of the insulating space in the part connecting the end walls of the inner container so that it is only a few millimeters. In the case of such a design the walls of the inner and outer containers have to reliably keep to their set spacing and more particularly in the case of high vacuum insulation it is necessary to prevent contact between the containers.
It has turned out that a spring only associated with one end wall is not able to ensure such fixation in position. Owing to expansion and contraction due to thermal effects during the production and operation different absolute values may be assumed adjacent to the suspension means of the inner container associated with the two end walls, that is to say in the case of a suspension load adjacent to the one end wall by tension at the other wall the suspension may allow movement between the inner container and itself or, respectively, the outer container, in consequence of which the outer and the inner containers will move out of their parallel relative position. The occurrence of undesired vibrations or rattling noises may then not be prevented and furthermore the insulating effect may be impaired.